Coleman — NepJieline and other Syenites in Ontario. 149 



gneissoid structure so common there, nor Laving dikes of peg- 

 matitic rock consisting of lar^e individuals of nepheline and 

 muscovite. Xor are they like specimens from Barkevig, 

 Norway, nor Litchfield, Maine, but some of them have much 

 the appearance of specimens sent by Professor Pirsson from 

 Highwood Mts., Montana, and Red Hill, Moultonborough, 

 ^Q\^ Hampshire, having a tendency to flat plate-like forms of 

 the feldspars, and long prisms of the darker minerals. These 

 would apparently be classed by Professor Brdgger as foyaites, 

 though unlike a specimen of foyaite from Lougenthal, Norway, 

 sent me by Dr. Washington. 



In the considerable number of specimens collected near Port 

 Coldwell four fairly well marked types may be distinguished, 

 so far as megascopic structure is concerned : 



1. Medium to coarse-grained gray rocks having a dioritic 

 appearance with light and dark minerals in about equal 

 amounts and the grains isodiametric. 



2. Medium-grained, reddish, purplish or violet-gray rocks, 

 with about twice as much of the lighter colored minerals as of 

 the darker ones, and with a tendency to plate-like or elongated 

 forms in the minerals. 



3. Yiolet-gray, tine-grained rocks with porphyritic feld- 

 spars and other minerals. 



4. Narrow veins of coarse-grained rocks, often mottled 

 with red, gray and black. 



There are, however, many intermediate varieties between 

 the four here mentioned, illustrating the usual variability of 

 the nepheline rocks. 



1. The tirst variety occurs as fresh looking material about 

 two miles east of Port Coldwell, and was supposed to be diorite 

 when collected. The white minerals are nepheline, orthoclase, 

 and a less amount of finely striated plagioclase having a very 

 small extinction angle, probably oligoclase ; all badly weathered 

 and turbid, the nepheline sometimes changed into a brown- 

 ish substance having aggregate polarization, perhaps a zeolite. 

 The dark minerals include hornblende in fairly well formed 

 crystals having a pleochroism of dark green, brownish green and 

 brown, and an extinction angle of 23° ; and also augite in about 

 equal amounts, sometimes enclosed in the hornblende. The 

 augite has a slight pleochroism, sea-green, gray-green and 

 brownish green, but its extinction angle is normal and the 

 nearly rectangular cleavages in cross sections show that it is 

 really a pyroxene. The only accessory minerals noticed are 

 magnetite and apatite, both in considerable quantities. 



A very similar but duller rock occurs in the tirst railway cut 

 west of Port Coldwell, with the difference, as seen under the 

 microscope, that the hornblende is dark brown and the augite 



